I may have found a coin referenced here... 1971 D No FG What do you guys think? It will be added to my collection.
The difference between yours and the one in the reference is that yours is a debris filled die. The ones referenced also have what is called a floating roof. This is caused by an over polishing of the die and the relief of the devices are now gone most notable at the top roof of the Memorial.
As P&G said, it is probable that yours was the result of a grease-filled die since I see no indication of over-polishing in the area of the designer's initials.
